(a) Field of the Invention
This invention related to diamine salts of 1-alkyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid, to solutions containing said salts and to a process for their preparation.
(b) Description of the Prior Art
Sterling Drug Inc. G. Y. Lesher and M. D. Gruett U.S. Pat. No. 3,590,036, issued June 29, 1971, shows, inter alia, 1-alkyl-1,4-dihydro-4-oxo-7-alkyl-1,8-naphthyridine-3-carboxylic acids and salts thereof as antibacterial agents, a preferred embodiment being 1-ethyl-1,4-dihydro-7-methyl-4-oxo-1,8-naphthyridine-3-carboxylic acid, a commercially available drug generically known as nalidixic acid. Among the salts shown are the 3-carboxylic cationic salts with preferred salts being:
"These comprise the alkali metal salts, e.g., the sodium or potassium salts; the lower-alkaline earth metal salts, e.g., magnesium or calcium salts; and, the ammonium or organic amine salts, e.g., diethanolamine or N-methylglucamine salts."
Among the organic cationic salts specifically disclosed for nalidixic acid are its N-methylglucamine salt (Example 108) and its 4-sulfamoylbenzylammonium salts (Example 349).
An abstract [C.A. 76, 126372k (1972)] of Soc. d'Etudes de Produits Chimiques French Demande 2,070,673, filed Oct. 22, 1971, shows virustatic alkylenediamine salts which were prepared by reaction of ethylenediamine (I) with the appropriate acid in refluxing methanol or by reacting the calcium salt of the appropriate acid with ethylenediamine dihydrochloride in water. Shown are the following salts of ethylenediamine: "camphorate, .alpha.-furoate, 5-nitro-.alpha.-furoate, 5-bromo-.alpha.-furoate, cyclohexamate, 2-oxobornane-3-sulfonate, pyridinesulfonate, benzoate, 5-methyl-8-hydroxyquinoline-7-sulfonate, nicotinate, .beta.-dodecylsulfate and thiophenesulfonate". These compounds are also shown in the corresponding British Pat. Nos. 1,176,077 and 1,268,557, published respectively on Jan. 1, 1970 and Mar. 29, 1972.
Belgian Pat. No. 827,639, published July 31, 1975 shows, as agents for treating respiratory tract infections, and as having bronchodilator, respiratory analeptic and mucolidic activities, salts of ethylenediamine with theophylline alkanoic acids and S-containing amino acids. Preferably used were 7-theophylline acetic acid or its 8-chloro or bromo derivative and the S-containing amino acids used were cysteine, methionine, N-acetyl-methionine, N-acetyl-thiazolidine carboxylic acid, N-acetyl-cysteine or S-carboxymethyl cysteine. The corresponding U.S. Pat. No. 4,071,517, issued Jan. 31, 1978.